Catheters have been in existence for various purposes, including draining of abscess and for urinary issues, since the 19th century. Dialysis involve the process of cleaning toxins present in large quantities in patients' blood through a filter membrane, using a pump process, and then returning the clean or dialyzed blood back to the patient. In the 1960s dialysis was discovered as a tool of improving survival in patients with end stage kidney disease or kidney failure. The patient blood is obtained from a large central vein via a dialysis catheter, which includes tubes that allow blood to be drawn from the patient, the blood then being processed through a dialysis machine and returned back to the patient through a different part of the tubes or dialysis access.
FIG. 1 illustrates a conventional in vitro dialysis catheter 100 in vitro, in accordance with one embodiment. The dialysis catheter 100 comprises a lumen tube 112 having a distal end 102 and a proximal end 104. The proximal end 104 bifurcates into limbs 106, each of which includes one or more clamps 110. The limbs 106 terminate at limb ports 108. FIG. 2 illustrates a dialysis catheter insertion process 200 in accordance with one embodiment. To insert the dialysis catheter, first cannulate the central vein with a needle at an insertion site 202. Next, advance a guidewire into the central vein 204, and remove the needle 206. Next, tunnel from the insertion site to create a tunneled layer 208, and insert the dialysis catheter through the tunneled layer and over the guidewire 210. Then remove the guidewire 212 and insert sutures at an exit site of the dialysis catheter 214, and insert sutures at the insertion site 216.
In some cases, a peel away sheet is deployed over the guidewire to facilitate removal of the guidewire and placement of the tunneled dialysis catheter at the insertion site. This technique may require use of a flow valve.
Next, align the dialysis catheter such that limb ports of the dialysis catheter are outside the tunneled layer 218, and deploy occluding clips on the limb ports 220, and anchor the limb ports to the skin 222.
Initially at the advent of dialysis, access to the patient blood was mainly via such tubes. Recently, AV grafts and AV fistulas have become the preferred method for accessing the blood, due to lower risk of infection. Dialysis catheters are still common in patients starting dialysis for the first time, and in many others who cannot tolerate a fistula or graft. The advantage of the dialysis catheter includes easy access and early use from the time of insertion to the time when dialysis is needed. A major disadvantage is the high risk of infection.
Studies have shown that in long term dialysis patients using a tunneled dialysis catheter, the exit site of the dialysis catheter infection is strongly correlated to the exit site bacteria contamination. Prevention of swimming or exposure to water has been tried to minimize recurrent infection or bacterial contamination of the exit site. However, the exposure of the catheter exit site to the skin results in a high chance of bacteria migrating to contaminate the dialysis catheter and subsequently cause bacteremia infections.
In the early 1990s, an entirely subcutaneous dialysis catheter called Life Site was introduced, but was not shown to decrease dialysis catheter related infections. The Life Site catheter utilized a complex valve system, involving multiple metallic and silicone layers inside the valves.